Image quality enhancement of CT hepatic portal venography using dual energy blending with computer determined parameters

BACKGROUND: Previous studies have shown that using some post-processing methods, such as nonlinear-blending and linear blending techniques, has potential to improve dual-energy computed (DECT) image quality. OBJECTIVE: To improve DECT image quality of hepatic portal venography (CTPV) using a new non-linear blending method with computer-determined parameters, and to compare the results to additional linear and non-linear blending techniques. METHODS: DECT images of 60 patients who were clinically diagnosed with liver cirrhosis were selected and studied. Dual-energy scanning (80 kVp and Sn140 kVp) of CTPV was utilized in the portal venous phase through a dual-source CT scanner. For image processing, four protocols were utilized including linear blending with a weighing factor of 0.3 (protocol A) and 1.0 (protocol B), non-linear blending with fixed blending width of 200 HU and set blending center of 150HU (protocol C), and computer-based blending (protocol D). Several image quality indicators, including signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and contrast of hepatic portal vein and hepatic parenchyma, were evaluated using the paired-sample t-test. A 5-grade scale scoring system was also utilized for subjective analysis. RESULTS: SNR of protocols A-D were 9.1±2.1, 12.1±3.0, 11.6±2.8 and 14.4±3.2, respectively. CNR of protocols A-D were 4.6±1.3, 8.0±2.3, 7.0±2.0 and 9.8±2.4, respectively. The contrast of protocols A-D were 37.7±11.6, 91.9±21.0, 66.2±19.0 and 107.7±21.3, respectively. The differences between protocol D and other three protocols were significant (P < 0.01). In subjective evaluation, the modes of protocols A, B, C, and D were rated poor, good, generally acceptable, and excellent, respectively. CONCLUSION: The non-linear blending technique of protocol D with computer-determined blending parameters can help improve imaging quality of CTPV and contribute to a diagnosis of liver disease.

Role of Endoscopic Ultrasound to Assess and Manage Portal Hypertension

Portal hypertension leads to the development of varices along the gastrointestinal tract. Endoscopy plays an important role in the diagnosis and management of varices. Endosonography (EUS) enables visualization and permits access to varices and veins outside the gastrointestinal tract. EUS has emerged as an important tool, with the ability to identify vascular changes, treat gastric and ectopic varices, perform portal pressure measurements, portal venography, and intrahepatic shunt placement. This review discusses the role of endoscopy and the emerging role of EUS in evaluation and management of portal hypertension.

Iodine load reduction in dual-energy spectral CT portal venography with low energy images combined with adaptive statistical iterative reconstruction

Objective: To study the application of using low energy images combined with adaptive statistical iterative reconstruction (ASiR) in dual-energy spectral CT portal venography (CTPV) to reduce iodine load. Methods: 41 patients for CTPV were prospectively and randomly divided into two groups. Group A ( n = 21) used conventional 120 kVp scanning protocol with contrast dose at 0.6 gI/kg while group B ( n = 20) used dual-energy spectral imaging with reduced contrast dose at 0.3 gI/kg. The 120 kVp images in Group A and 50 keV images in Group B were reconstructed with 40% ASiR. The contrast-to-noise ratio of portal vein was calculated. The image quality and the numbers of intrahepatic portal vein branches were evaluated by two experienced radiologists using a 5-point scoring system. Results: Group B reduced iodine load by 52% compared to Group A (17.21 ± 3.30 gI vs 35.80 ± 6.18 gI, p < 0.001). All images in both groups were acceptable for diagnosis. CT values and standard deviations in portal veins of Group B were higher than Group A (all p < 0.05); There were no statistical differences in contrast-to-noise ratio, image quality score and the number of observed portal vein branches between the two groups (all p > 0.05), and the two observers had excellent agreement in image quality assessment (all κ > 0.75). Conclusion: The use of 50 keV images in dual-energy spectral CTPV with ASiR reduces total iodine load by 52% while maintaining good image quality. Advances in knowledge: Spectral CT images combined with ASiR can be used in low contrast dose CTPV portal venography to maintain image quality and reduce contrast dose.

Evaluation of Collateral Circulation in Cirrhosis by Computed Tomography Portal Venography

Objective: Cirrhotic portal hypertension can lead to extensive collateral circulation in the portal vein system, and the esophagogastric variceal bleeding (EVB) can easily lead to death. Computed tomography portal venography (CTPV) can display the composition of portal vein noninvasively. The purpose of this study was to investigate the diagnostic value of CTPV in collateral circulation of cirrhosis and to predict the risk of EVB. Methods: A total of 37 patients with cirrhosis in our hospital were analyzed retrospectively. All patients underwent CTPV and gastroscope to observe and classify varicose veins. The consistency of the two methods was analyzed. The diameters of patients with major tributaries of portal vein were compared between the hemorrhagic and non-hemorrhagic patients. The receiver operation characteristic (ROC) curves were used to evaluate the predictive value for EBV. Patients with varicose veins underwent endoscopic esophagogastric variceal ligation. Results: The tributaries of portal vein and the collateral circulation was showed clearly in CTPV. The esophagogastric varices was found in 30 patients, and the Kim grades I, II and III were 8, 10 and 12 respectively. The varicose was found in 28 patients under gastroscope. The CTPV and endoscopy were highly consistent in grading of esophagogastric varices (kappa 0.674). Compared with the non-hemorrhagic patients, the diameter of SMV, LGV and SV in hemorrhagic patients increased significantly. The ROC curves of predicted EBU by these diameters were 0.64, 0.76, and 0.83, respectively. There was no statistical difference between the diameter of portal vein and its tributaries before and after endoscopic variceal ligation. Conclusion: The CTPV can show the collateral vessels of portal vein in patients with cirrhosis, evaluate the degree of varicosity, and determine the risk of varicose rupture.